The present invention relates to a technique for fabricating a transformer that has cores composed of lamination of thin magnetic material.
The present invention also relates to a transformer having amorphous-iron cores.
An amorphous-iron core transformer is disclosed in, for example, JP-A-2006-120879. In this Japanese patent document, the technical advantage is stated as follows. Since the amorphous-iron cores themselves stand upright without being supported by any supporting mechanism, the weights of the cores do not exerted on the windings, and lapping work does not depend on the shapes of finished windings so that lapping process can be stabilized. As a result, the characteristics of the cores and the workability of the process of insulating the cores from the coils can be both improved.
The transformer according to the Japanese patent document has its windings subjected to molding process using varnish impregnation in order to secure the resistance to short-circuit in the large-sized windings resulting from the demand for large power handling.
According to conventional methods of manufacturing transformers having amorphous-iron cores, when the windings and the amorphous-iron cores are assembled, the windings are kept upright and the amorphous-iron cores are inserted from above through the windings in the vertical direction, and then the assembly of the windings and the cores is laid down to lap the cores.
JP-A-10-189348 discloses a technique according to which both the lengthwise ends of the coil bobbin protrude beyond both the lengthwise ends of each winding when the turns of the winding have been wound around the coil bobbin so that when the amorphous-iron core is inserted through the winding, the insertion of the core through the winding can be facilitated and that the core can be prevented from damaging the inner side surface of the winding.